Lubricant for spraying on chemically coated metal surfaces



l l v United States Patent 2 ,849,107 runner-NT FOR- smarts-G: os ennvncrrtv COATED METAL SURFACES Earl Eugene ro ue; J11, BirminghanuMiclL, assignor'to Parker Rust. Proof Company, Detroit; Mich, a corporation' ofMichigarr NdDrawin'g; pbuc'atiqfla aai 26; 19%?" Serial No. 406,333 warms.- ell-105 2) The present invention relates; to manta-titwhen is useful in lubricating chemically coated; metal surfaces rior to deformation, and more'speificallyto a soap type lubricant whi'ch is capable of being applied to such metal surfaces by spraying without the formation of an e'ic es sive quantity of foam.

In the art of metal deforrr'iation or metal drawing, it is new customary to provide a chemical c'zoa'tirigv onthe metal surface to be drawn, su'ch asa pnosphate'maafig, an oxide coating; an oxalate coating, a sulfide coating or the like, and to treat such coating a lubricant, such as an aqueous soap solutionlprior to the ctua l deforma tion. In the processing of large articles, isiu'sually most convenient to apply the soap solution to the coated metal surface by spraying. However, upon spraying such aqueous soap solutions and especially when the solutions are hot, diificulty has been experienced due to the'formation of excessive quantities of foam. Large uantities of foam detrimentally interfere with continuous processing tiverflowingor altering the consistency of the solution'b'eiii'g pum ed mthe spray nozzles se' tnat only an inadequate quantity or solution is supplied-to thesu'rrace form a uniformly distributedlubficating l'ayer thereon. Attempts have been made toqve ieonrethis proble'niby employing a riumbei of special urpose aiiti fdarniri'g a entssncn as alcohols and snic'ones; but" peratin hot aqueous soap solutions; thealcohols are ubject to evaporation as noxious fumes andthe silicons are relatively expensive for this use.

In the fofrhatio'n of areactd lu'bricating-coatifigfrbfii a chemical coating, such as a phosphate coating-by the use of aqueous so'a solutions; it is necessary that the aq eous soap soliiti'on have carefully controlled pH in order for the coating and the aqueous soap solntiorl'to interreact to form the desired lubricating metallic soap. This pH range is approximately 8.8 to 10.5 as measured by the appropriate Hydrion" pl-I papers (paper #460 for the lower numerical limit and paper #470 for the upper numerical limit),- and these limits correspond to a pH of 8.2 to 9.6 as determined-by using-a lithia-glass electrode pH meter. Whenthis pH condition prevails, and a metal phosphate coating is contactedwith a hot aqueousso'ap solution; a reaction occurs betweenthe soap solution and the metal of the phosphate coating to' form a metallic soap which is integral with the phosphate coating and is incapable of being washed oif. The-coating thus formed is grayish to white in color, smooth and velvety to the touch and crushes to a continuous unctuous film on the application of pressure; and this continuous film is ideal as a parting layer between the metal and the die during deformation operations.

The application of aqueous soap solutions in these ranges of pH by spraying while in the hot condition produces excessive quantities of foam.- Attempts to reduce the amount of foam which is fofihed in such soap solutions comprising the piocedure of regulating the'free fatty acid content relative to the total fatty acidby the 7 2,849,107 Patented Aug. 26, 1958 2 addition of mineral acids or excess free fatty acid, to an extent suflicient to eliminate the formation of excessive quantities of foam, have resulted in altering the pH of the solution to values numerically below the necessary limit to obtain the desired level of reactivity between the phosphate and the soap solution. In fact, when free fatty acid is present in a proportion necessary to control foam, the pH is reduced to the point at which the soap tends to congeal, thicken and become non-reactive with thephosphatecoating.

In accordance with this invention, it has now been found that the use of rosin acids, in the amounts specified hereinafter, in aqueous soap solutions provides simultaneously the desired ratio of free fatty acid to total fatty acid to control the formation of foam and also provides the necessary pH to obtain the desired interreaction between the soap solution and the phosphate coating. The incorporation of rosin acid, unlike mineral or straight chainfatty acids, in an aqueous soap solution does not appreciably alter the pH of the soap solution throughout the desired pH range as discussed in greater detail below.- However, the amount of free fatty acid present and the ratio of free fatty acid to total fatty acid are greatly increased, and thus the requisite conditions for l0w;foam formation andtheformation of coatings of high lubricating value are fulfilled.

Rosin acids which are suitable for the purposes of this invention may'beinthe form of commercialgum or wood rosin,- tall oil, or may be extracted from tall oil residues. As used in this specification and in the appended claims, the term' rosin acid is intended in its generally understood sense, and may include such specific acids as abietic acid, neo abietic acid, pimaric acid, levopimaric acid, dextropimaric acid, isodextropimaric acid and mixtures thereof.

Compositions of this invention in the form of an aqueous concentrate which, upon the addition of water, produce the reactive solutions of lowfoaming characteristics above described are set forth in Formula I, the range of proportions of the various ingredients being given inparts by weight.

FORMULA r K Parts by weight Saturated higher fatty acid or acids 22.5-70 Rosinacid' r 35-30 lkali metalhydroxide 3.5- 15 Water 50-140 The compositions of this invention may optionally include other ingredients which are now conventional in drawing compounds in minor proportions, such as mineral oils, coloring and scenting compounds, etc. Mineral oils have been found to be desirable in quantities of about 2%10% by weight. The particular mineral oil which is employed is not critical. A wide variety of oils are availablecommercially under the designation of mineral oils and the specifications of a typical mineral oil which has been successfully employed in the compositions of this invention are as follows:

specific gravity 23 A. P. I. Viscosity (Saybolt):

210 37-40. Flash point Minimum temperature 320 F. Fire point Minimum temperature, 350 F. 'P'o'ur point- Minimum temperature, 25 F.

Preferrd compositions including mineral oil are set fOi'thiii Formula II.

3. FORMULA H Parts by weight Saturated higher fatty acid or acids 22.5-70 Rosin acid 3.5- Mineral oil 2-25 Alkali metal hydroxide 3.5-15 Water 140 The compositions given in Formulas I and II are relatively concentrated and may be concerted into a working solution for spraying on a phosphate coated surface by incorporating 30 to 460, but preferably to pounds of such compositions in gallons of solution.

The ratio of rosin acids to fatty acids in the concentrates of Formulas I and II has been found to be critical to the successful spraying of the working solutions of this invention. When the concentrate contains less than 3.5 parts of rosin acid per 22.5 parts of fatty acid, the foaming which is encountered on spraying a Working solution prepared therefrom is excessive. If more than 30 parts of rosin acid per 70 parts of fatty acid are present in the concentrate, the reaction of the solution with the phosphate-coated surface is decreased to the point such that the resultant reacted coating is not of the desired character, that is, it is no longer a White velvety coating and can be easily removed from the surface with water.

The method of this invention comprises the steps of spraying a working solution on a metal surface which has been preliminarily coated with a phosphate coating, an oxalate coating, a sulfide coating or an oxide coating at a temperature of about F. to 200 F. for sufiicient time to permit the sprayed lubricant to penetrate the coating and to bring the metal being sprayed up to the temperature of the lubricant, this usually requiring about 1 to 5 minutes. Although the temperature of operation is not critical, spraying becomes more diflicult at lower temperatures because the solution tends to become somewhat thicker and drains from the work at a much slower rate. After the chemically coated article has been sprayed for the 1 to 5 minute interval, the solution is allowed to-drain therefrom after which the reacted coating should be dried. Drying may be accomplished by allowing the article to remain at room temperature for a sufficient length of time, or by the use of heated air or a dry-01f oven maintained at a temperature of about F. to 225 F. In the use of the working solutions of this invention, it is necessary to control both the pH and the free acid content respectively in order to obtain the maximum reactivity with the phosphate coating and to avoid the formation of excessive quantities of foam. It has been found that the pH should be maintained in the range of 8.8 to 10.5 and preferably in the range of 9.4 to 10.0 as determined by the use of Hydrion pI-I papers and the free acid should be maintained in a definite relar tion to the Babcock number as defined below. As metal is treated in the solutions of this invention by spraying, the active ingredients of the solution are gradually consumed. The proper concentrations of the active ingredients may be maintained by maintaining the Babcock =2 separated sharply, usually in about half an hour, the

difference between the readings of the lower and upper edges of the oily column in the neck is the Babcock number. For best operation, the Babcock number is pref erably maintained in the range of 2.5 to 3.0, and as the Babcock number decreases below 3.0, sufficient con- 4 centrated solution should be added to increase the Babcock number up to about 3.0.

The free acid in the solution means the fatty acid which is uncombined and not in the form of a soap. Free acid in the operating solution is determined by adding 200 ml. of 99% isopropyl alcohol containing a small amount of phenolphthalein indicator to a 10 ml. sample of the aqueous working solution. This solution is then heated to boiling and titrated while hot with a 0.1 N aqueous solution of sodium hydroxide to the development of a permanent pink color. The number of milliliters of sodium hydroxide solution required to attain the permanent pink color is known as points of free acid. The free acid value, for best results, varies with the Babcock number and should be 0.3 to 1.3 points higher than the Babcock number. The free acid may be controlled by adding caustic soda or mineral acid to the working solution as required to compensate for dragin effects. When the free acid is maintained within the above given numerical range and when the concentration of the active ingredients in the working solution is maintained by the use of the concentrate of Formulas I or II, the pH will be found to remain within the desired range of 8.8 to 10.5. The more eifective pH range of 9.4 to 10.0 is obtained when the Babcock number is maintained in the near vicinity of 3.0 and the free acid is maintained between 3.3 and 4.3, and these conditions represent the preferred operating conditions.

The examples given below are intended to illustrate the compositions and the method of this invention in somewhat greater detail.

Example 1 A soap concentrate was made up by admixing 225 grams of stearic acid, and 75 grams of gum rosin and 20 grams of mineral oil (specification given hereinbefore), 26 grams NaOH and 310 grams water at 200 F. to 210 F. for about 10 minutes with slow stirring to produce a thick paste at room temperature. The thick paste was then diluted with Water to 6 liters in volume and the working solution so formed was found to have a Babcock number of 3.2 to 3.5. The solution was sprayed at a tempeerature of 160 F. on a number of 4" X 6" mild steel panels, which had been preliminarily coated with a conventional zinc phosphate coating, for about one-half minute to one minute. The coatings were dried in an oven at 170 F. to 225 F. and inspected. The coating which was the reaction product of the zinc phosphate coating and the sprayed solution was gray to whitish in color and soft, velvety and capable of being crushed to a continuous unctuous film.

Example 2 A 250 gallon working solution was prepared by adding 187 pounds of a concentrate, having the composition given below, to sufficient water to give 250 gallons of solution. The concentrate used contained 26.2 parts stearic acid, 10.5 parts rosin acid, 7.9 parts mineral oil (specification given hereinabove), 3.6 parts sodium hydroxide and 51.8 parts water. The tank containing this working solution was operated at a temperature between F. and F. as one unit in the continuous spray processing of annealed 76 mm. steel cartridge case components prior to drawing, the complete processing including the steps of pickling, rinsing, phosphate coating, rinsing and spraying with the solution of this tank for l to 3 minutes and drying. After 3% weeks of operation, during which time about 75,000 pieces were lubricated and drawn, no trouble was encountered due to excessive foaming of the solution and the quality of the lubricating coating remained consistently satisfactory for relatively severe draws. The same bath was still operating satisfactorily after 6 months under normal production conditions.

Example 3 A working solution was repared by admixing 300 grams stearic acid, 120 grams rosin acid, 90 grams mineral oil, 6 grams pine oil, 42 grams sodium hydroxide and 522 grams of water at 200 F. to 210 F. for about 10 minutes, and the admixture was then diluted to 8 liters with water. The pH of the solution was found to be 9.2. No excessive foaming was encountered in spraying this solution at 180 F. to 190 F. and the quality of the lubricating coating resulting from contacting phosphate coated panels therewith was found to be satisfactory for protecting the metal during relatively severe drawing operations.

A plurality of panels were individually provided with an oxalate coating, others with a sulfide coating and' still others with an oxide coating, all processes for producing these coatings being conventional. When these panels were contacted with the above composition at a temperature of 180 F. to 190 F., lubricating coatings suitable for protecting the metal during relatively severe drawing operations were obtained.

What is claimed is:

1. A lubricant composition for application to chemically coated metal surfaces which consists essentially of the product resulting from the admixture of the following ingredients in the quantities indicated in parts by weight:

Saturated higher fatty acid 22.5-70 Rosin acid 3.5-30 Alkali metal hydroxide 3.5- Water 50-140 the ratio of rosin acid to fatty acid being in the range of 3.5 :22.5 and 30:70, said product when diluted in the ratio of 30 lbs-460 lbs. per 100 gallons of solution produces a solution having a Babcock number in the range of 2.5-3.0, a free acid value of 0.3-1.3 points higher than the said Babcock number and a pH in the range of 8.8- 10.5.

2. A lubricant composition for application to chemically coated metal surfaces which consists essentially of the product resulting from the admixture of the following ingredients in the quantities indicated in parts by weight:

and about 2%10% by weight of mineral oil, the ratio of rosin acid to fatty acid being in the range of 35:22.5 and 30:70, said product when diluted in the ratio of 30 lbs. to 460 lbs. per 100 gallons of solution produces a solution having a Babcock number in the range of 2.5- 3.0, a free acid value of 0.3-1.3 points higher than the said Babcock number and a pH in the range of 8.8-10.5.

3. A lubricating composition for spray application to chemically coated surfaces which consists essentially of an aqueous solution containing 30 to 460 pounds per 100 gallons of solution of a concentrate which is the product of admixing the following ingredients, in parts by weight:

Saturated higher fatty acid 22.5-70 Rosin acid 3.5-30 Alkali metal hydroxide 3.5-15 Water -1 50-140 said solution having a Babcock number in the range of 2.5-3.0, a free acid value of 0.3 to 1.3 points higher than the said Babcock number and a pH in the range of 8.8 to 10.5.

4. A lubricating composition for spray application to chemically coated surfaces which consists essentially of an aqueous solution containing 30 to 460 pounds per gallons of solution of a concentrate which is the product of admixing the following ingredients, in parts by weight:

Saturated higher fatty acid 22.5-70

Rosin acid 3.5-3 0 Alkali metal hydroxide 3 .5-15 Water 50-140 and about 2% to 10% by weight of mineral oil, the ratio of rosin acid to fatty acid being in the range of 35:22.5 and 30:70, said solution having a Babcock number in the range of 2.5 to 3.0, a free acid value of 0.3 to 1.3 points higher than the said Babcock number and a pH range of 8.8 to 10.5.

5. The method of deforming chemically coated metal which comprises the steps of contacting chemically coated metal by spraying with an aqueous solution consisting essentially of 30 to 460 pounds per 100 gallons of solution of a concentrate which is the product of admixing the following ingredients, in parts by weight:

Saturated higher fatty acid 22.5-70 Rosin acid 3.5-30 Alkali metal hydroxide 3.5-15 Water 50-140 and about 2%10% by weight of mineral oil, the ratio of rosin acid to fatty acid being in the range of 3.52225 and 30:70, said solution having a pH in the range of 8.8 to 10.5, a Babcock number in the range of 2.5 to 3.0 and a free acid value of 0.3 to 1.3 points higher than the Babcock number, drying the coating and thereafter deforming the metal.

6. The method of spraying chemically coated metal surfaces in the absence of excessive foam formation with an aqueous solution consisting essentially of 30 to 460 pounds per 100 gallons of solution of a concentrate which is the product of admixing the following ingredients, in parts by weight:

and about 2%10% by weight of mineral oil, the ratio of rosin acid to fatty acid being in the range of 35:22.5 and 30:70, said solution having a pH in the range of 8.8 to 10.5, a Babcock number in the range of 2.5 to 3.0 and a free acid value of 0.3 to 1.3 points higher than the Babcock number, drying the coating and thereafter deforming the metal.

References Cited in the file of this patent UNITED STATES PATENTS 93,102 Lowery July 27, 1869 462,229 Armstrong Nov. 3, 1891 1,304,399 Southcombe May 20, 1919 1,621,483 Dimmig Mar. 15, 1927 1,882,721 Arveson Oct. 18, 1932 1,907,920 Wilkin May 9, 1933 1,982,198 Brunstrum et al. Nov. 27, 1934 2,129,422 Hall Sept. 6, 1938 2,588,234 Henricks Mar. 4, 1952 2,613,626 Whitney Oct. 14, 1952 2,672,976 Overath Mar. 23, 1954 2,673,838 Veatch et a1. Mar. 30, 1954 OTHER REFERENCES Metalworking Lubricants-Bastin-McGraw-Hill Book Co., Inc. (N. Y.), 1951, pages 65, 69 and 71. 

5. THE METHOD OF DEFORMING CHEMICALLY COATED METAL WHICH COMPRISES THE STEPS OF CONTACTING CHEMICALLY COATED METAL BY SPRAYING WITH AN AQUEOUS SOLUTION CONSISTING ESSENTIALLY OF 30 TO 460 POUNDS PER 100 GALLONS OF SOLUTION OF CONCENTRATE WHICH IS THE PRODUCT OF ADMIXING THE FOLLOWING INGREDIENTS, IN PARTS BY WEIGHT: 